A process for manufacturing a liquid crystal panel, which is an example of a semiconductor substrate, roughly includes an array (TFT) step, a cell (liquid crystal) step, and a module step. In the array step among these steps, gate electrodes, a semiconductor film, source/drain electrodes, a protection film, and transparent electrodes are formed on a transparent substrate, and then array detection is performed, so that the presence/absence of a short circuit of wiring, such as an electrode or a wiring line, is detected.
Normally, in array detection, such a fault is specified by causing a probe to be in contact with an end portion of a wiring line and measuring an electric resistance at both ends of the wiring line or an electric resistance and electric capacitance between wiring lines adjacent to each other. However, even if the presence/absence of a fault in a wiring portion can be detected through array detection, it is not easy to specify the position of the fault.
For example, as a method for addressing the above-described problem and specifying the position of a fault, infrared detection is available in which a voltage is applied to a leak fault substrate to generate heat, and the position of a fault is specified using an image that is captured by an infrared camera and that indicates the temperature of the surface of the leak fault substrate.
PTL 1 relates to infrared detection in which a short-circuit fault of a substrate is detected using an infrared image. With a difference image representing the difference between infrared images of substrates before and after a voltage is applied, a wiring line in which heat is generated can be detected, and the position of the fault can be specified.
Further, PTL 2 discloses a failure diagnosis method using an infrared camera.